Effects Of Electroacupuncture Preconditioning On Myocardial Akt/mTOR Pathway In Rats With Myocardial Ischemia-reperfusion Injur

Objective: To observe the effect of electroacupuncture pretreatment on the autophagy-related pathway protein kinase B(Akt)/mammalian target of rapamycin(mTOR)in myocardial tissue of rats with myocardial ischemia reperfusion injury(MIRI),and explore the protective effect mechanism of "Neiguan" acupoint on MIRI.Methods: 48 rats were randomly divided into a blank group,a sham-operated group,a model group and an endocannabinoid group.The MIRI model was established by ligating the left anterior descending branch of the coronary artery in the model group.In the Neiguan group,the rats were continuously stimulated with electroacupuncture for 30 min for 7 days before modeling,once a day.In the remaining groups,the histomorphological changes in the myocardium were observed by HE staining and transmission electron microscopy;the serum p-Akt and p-mTOR levels were measured by ELISA;the expression levels of Akt,p-Akt,mTOR and p-mTOR in the myocardium were measured by Western blot.Results:1.Myocardial tissue morphology:In the blank group,myocardial fibers were neatly arranged,and no inflammatory cell infiltration and hemorrhage were seen in the interstitium;in the sham-operated group,myocardial fibers were slightly irregularly arranged,not broken,and a small number of mitochondrial vacuoles were visible;in the model group,myocardial fibers were disordered in distribution,hypertrophic cardiomyocytes were increased,and inflammatory infiltration and hemorrhage were seen in the interstitium,and a large number of autophagic vesicles and vacuoles were visible;in the Neiguan group,myocardial tissue lesions were less severe than in the model group,a small amount of interstitial hemorrhage and inflammatory cell infiltration were seen,and the number of autophagic vesicles was reduced.2.Serum p-Akt,p-mTOR levels:Compared with the sham-operated group,serum p-Akt was significantly lower(P<0.01)and serum p-mTOR was lower(P<0.05)in the model group;compared with the model group,serum p-Akt was elevated(P<0.05)and serum p-mTOR was significantly elevated(P<0.01)in the rats in the endograft group.There was no statistically significant difference between the blank group and the sham-operated group(P>0.05).3.Myocardial tissue Akt,p-Akt,mTOR and p-mTOR expression and p-Akt/Akt and p-mTOR/mTOR ratios:The levels of p-Akt,p-mTOR and p-Akt/Akt,p-mTOR/mTOR in the model group decreased compared with the sham-operated group(P<0.01);the levels of p-Akt,p-mTOR and p-Akt/Akt,p-mTOR/mTOR in the endograft group increased compared with the model group(P<0.01).The differences in Akt and mTOR levels in myocardial tissue of rats in each group were not statistically significant(P>0.05);the differences in p-Akt and p-mTOR protein expression and p-Akt/Akt and p-mTOR/mTOR ratios in myocardial tissue of rats in the blank group and sham-operated group were not statistically significant(P>0.05).Conclusion:1.Electroacupuncture pretreatment reduced myocardial infarct size,decreased myocardial cell necrosis and improved symptoms of ischemia-reperfusion injury in rats.2.Electroacupuncture pretreatment attenuates MIRI and acts as a myocardial protector,and the mechanism may be related to activation of the Akt/mTOR pathway and thus inhibition of excessive autophagy.